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🛡️ Sentinel: Fix Content Spoofing Vulnerability #24

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🛡️ Sentinel: Fix Content Spoofing Vulnerability #24

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5 changes: 5 additions & 0 deletions .jules/sentinel.md
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Expand Up @@ -22,3 +22,8 @@
**Vulnerability:** The `ImageLoader` and `VideoURLProvider` scripts validated and upgraded URLs to HTTPS in their string cache for comparisons, but failed to update the actual `VRCUrl` objects used for the download/playback requests. This meant the code *looked* secure (validating strings) but *acted* insecurely (requesting HTTP), creating a false sense of security and leaving users vulnerable to MITM attacks.
**Learning:** Validating a shadow copy (cache) of data does not secure the source data. When using object wrappers (like `VRCUrl`), modifying the extracted value does not modify the object itself. Security upgrades must be applied to the actual objects used for operations.
**Prevention:** Explicitly replace or upgrade the source objects (e.g., `predefinedUrls[i] = new VRCUrl(secureUrl)`) when sanitizing inputs, rather than just sanitizing the local variable used for logic checks.

## 2025-05-22 - Prevent Content Spoofing via Fallback Logic
**Vulnerability:** `FindMatchingUrlIndex` contained a fallback mechanism that blindly mapped unknown URLs from external lists to existing, unrelated `VRCUrl` slots when `useGeneratedUrlData` was enabled. This allowed external configuration to apply arbitrary captions to pre-approved images, creating a spoofing vulnerability.
**Learning:** Convenience features (like "auto-mapping" or "cyclic assignment" for unmatched items) often undermine strict allowlist enforcement. "Fail Closed" means if an exact match isn't found, the operation must fail, not guess.
**Prevention:** Remove fallback logic that bypasses exact matching. Ensure that lookups against an allowlist return an error or empty result if the specific item is not found.
13 changes: 0 additions & 13 deletions Scripts/ImageLoader.cs
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Expand Up @@ -457,19 +457,6 @@ private int FindMatchingUrlIndex(string urlToFind, int additionalCount = 0)
}
}

// If using generated data, we can use the cyclical assignment
if (useGeneratedUrlData)
{
// Use the next available predefined URL slot (cyclical)
int index = (_activeUrlIndices.Length + additionalCount) % urlCount;

// Ensure the predefined URL at this index exists
if (index < _predefinedUrlStrings.Length && _predefinedUrlStrings[index] != null)
{
return index;
}
}

// Last resort: find any available predefined URL
// REMOVED for security: preventing content spoofing.
// If the URL is not found in the predefined list, we should NOT display a random image.
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29 changes: 0 additions & 29 deletions Scripts/VideoURLProvider.cs
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Expand Up @@ -1040,35 +1040,6 @@ private int FindMatchingUrlIndex(string urlToFind, int additionalCount = 0)
}
}

// If using generated data, we can use the cyclical assignment
if (useGeneratedUrlData)
{
// Use the next available predefined URL slot (cyclical)
// Include additionalCount to account for items currently being batched
int index = (_activeUrlIndices.Length + additionalCount) % urlCount;

// Ensure the predefined URL at this index exists
if (index < _predefinedUrlStrings.Length && _predefinedUrlStrings[index] != null)
{
// Check if this URL is already used
string newUrl = _predefinedUrlStrings[index];
for (int j = 0; j < _activeUrlIndices.Length; j++)
{
int existingIndex = _activeUrlIndices[j];
if (existingIndex < _predefinedUrlStrings.Length && _predefinedUrlStrings[existingIndex] != null)
{
if (_predefinedUrlStrings[existingIndex] == newUrl)
{
Debug.Log($"[VideoURLProvider] URL already exists in playlist, skipping duplicate: {newUrl}");
return -1; // Skip adding duplicate
}
}
}

return index;
}
}

// Last resort: find any available predefined URL
// REMOVED for security: preventing content spoofing.
// If the URL is not found in the predefined list, we should NOT display a random video.
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